Writers of novelists have their works publicly available. What about someone who writes documentation for the launch code for nuclear submarines? While I will probably never ever see that documentation, it's really important that it is done well.

A corporate lawyer may produce a whole bunch of excellent work that the outside world never sees. Yet he keeps the company complaint with regulations.

If we were to do "show me the github" for stonemasons, we would want to see the pretty works of art that someone has made and select for that. But what about the guy who worked for 20 years laying the stone to keep the buildings up? He can't show off his work. But if I work in his building every day, I'm going to care a lot more that he was selected based on his ability to choose the stone that keeps buildings up than on his art.

The majority of code never sees the light of day. We are much more like miners than mathematicians in that the public cannot see our immediate work product, only the results after it has worked as a team. If you've never been hired you obviously can have all of your stuff public, but that's just selecting against people who have worked.

Analogies are hard.